/in/foo.cc: In function 'int main()':
/in/foo.cc:205:6: warning: unused variable 'cnt' [-Wunused-variable]
  int cnt=0;
      ^~~
/in/foo.cc: In instantiation of 'void read(T&) [with T = int]':
/in/foo.cc:198:8:   required from here
/in/foo.cc:172:16: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
         x = (x + (x << 2) << 1) + (c ^ '0');
              ~~^~~~~~~~~~